1. Field of the Invention
The present invention relates to a cooling device for a heat source that cools a heat source such as a semiconductor element.
2. Description of the Related Art
FIG. 1 shows cross-sectional views of a prior art cooling device for a heat source, FIG. 1A being a c cross-section, FIG. 1B being an a cross-section and FIG. 1C being a b cross-section.
In FIG. 1A to C, 1 are heat sources such as semiconductor elements, 2 is a heat sink, 3 are holes, 4 are headers, 5 is an inlet port, 6 is an outlet port, 7a is an inlet-side flow path, and 7b is an outlet-side flow path; cooling medium (hereinbelow “fluid”) entering from inlet port 5 passes through outlet-side flow path 7a and collides with the wall face of heat sink 2 where the heat sources are arranged from headers 4 from holes 3 and then flows through outlet-side flow path 7b and is discharged from outlet port 6. The arrows indicate the flow of the fluid.
The heat that is generated in the heat source is transmitted to heat sink 2 by thermal conduction and is transmitted to the fluid flowing out from holes 3 by thermal conduction. In this process, the cooling performance is raised by the fact that the rate of heat conduction (so-called, heat condition rate) is increased since the fluid, rather than merely flowing, collides with the heat sink as a spray from holes 3.
Also, although, in the case of a channel-type heat sink, there is considerable pressure loss since the fluid passes through narrow channels, with the spray system using holes, pressure loss is smaller than in the case of channels, so the cooling performance is higher.
However, with the conventional cooling device for a heat source, although the fluid is guided from the inlet port to the respective holes by inlet-side flow path 7a, there are considerable differences in the liquid frictional resistance between the respective flow paths, with the result that the flow rate from the holes is uneven, producing local differences in cooling performance.
A further problem is that, although the pressure loss is less than in the case of the channel type, the pressure loss may still not necessarily be capable of being described as small; this inevitably lowers the flow rate, due to limitations on the cooling liquid circulation pump and so lowers the cooling performance.